Currently, mesoporous materials are gaining importance for catalytic applications due to facile diffusion of molecules in their pores and for transformation of large, bulky molecules through catalysis. The immobilization of homogeneous catalyst on to the mesoporous solid surface is one of the vital applications of the mesoporous materials as the composite catalyst can give higher acidity while eliminating the complications involved in handling and separation of liquid acids that generally occur in multiple steps and which are time consuming. Particularly, the mesoporous silica obtained is finding variety of applications such as gas adsorption and for incorporation of metal to prepare bi-functional catalysts for various catalytic applications.
However, the art of synthesis requires specific preparation procedures that necessarily involve use of high cost ionic surfactants and block co-polymers as templating agents to drive the reactants towards the structure specific mesopores. Moreover, such template materials are also harmful and needs additional synthesis steps performed at high temperatures for template removal before using them for catalytic applications. The art of catalyst design lies in obtaining the well dispersed active sites in a high surface area porous material. Further, art of synthesis requires multiple step procedure following carbonization followed by sulfonation steps that limits the amount of acid bearing carbon sites (sulfonyl groups) which are required for the catalytic activity.
References may be made to U.S. Pat. No. 7,014,799 and U.S. Pat. No. 7,763,665 that describe the synthesis of mesoporous oxides where amphiphilic block copolymer is used as templating agent. However, the said process uses costly amphiphilic block copolymer and also involves lengthy procedure.
Reference may be made to US patent publication number 20050063890 that describes formation of mesoporous mixed oxide such as porous silica using amphiphilic surfactant as template. However, the drawback of this process lies in obtaining good connectivity between the macro pores and mesopores and exhibits broad distribution of pores.
References may be made to U.S. Pat. No. 6,696,258 that describes synthesis of various mesoporous oxides such as silica, alumina using glucose and other monosaccharides. But the process involves lengthy reaction time and procedures with steps such as pH adjustment with base and solvent extraction of the inner material to obtain the porous solids.
Reference may be made to S. Van de Vyver, L. Peng, J. Geboers, H. Schepers, F. de clippel, C. J. Gommes, B. Goderis, P. A. Jacobs and B. F. Sels, Green Chem., 2010, 12, 1560, where expensive block copolymer is used as a carbon source with two separated multiple steps procedure involving carbonization followed by sulfonation to obtain the acid functionality in the catalyst. The limitation of this process involves the use of expensive material and the two separated step procedure, one involving carbonization and the other involving sulfonation, limits the amount of acid sites that are required for the catalytic applications.
Reference may be made to P. Gupta and S. Paul, Green Chem., 2011, 13, 2365 where variety of mono and disaccharides are used as carbon source. But the method follows two separated step procedure, one involving carbonization and the other involving sulfonation that limits the formation high number of acid sties on the already carbonized material.
Further, the alkylation of phenol and the conversion of Glycerol into solketal (ketal of glycerol) are of great industrial importance. Some 450,000 tonnes of alkylated products like tertiary butyl phenols are used in the industry per year. Mono-alkyl phenols and di-alkylphenols are used in the manufacture of antioxidants, UV absorbers and for the production of phenolic resins. Literature review reveals that these alkylation reactions are mostly carried out in the gas phase with high conversion of phenol. However, gas phase reactions usually involve high temperature and pressure leading to high cost. Very few studies on the solvent state alkylation of phenol with tertiary butyl alcohol (TBA) have been published. These solvent state reactions however, usually show very low conversions, i.e., less than 50%. It will therefore be advantageous to find new environmental friendly catalysts and milder experimental conditions to increase output or to reduce cost or to satisfy the environmental needs.
Reference may be made to K. R. Sunajadevi and S. Sugunan, Catalysis Letters, 2005, 99, 3 where sulfated titania is used as catalyst for the tertiary butylation of phenol in vapour phase from temperature 453 K. However, the catalyst is not effective as it gives limited phenol conversion only up to 36% (wt. %).
Reference may be made to L. Li, T. I. Korányi, B. F. Sels and P. P. Pescarmona, Green Chem., 2012, 10.1039/c2gc16619d where heterogeneous Lewis acid catalysts such as Zr-TUD-1, Hf-TUD-1, Al-TUD-1,Sn-MCM-41 and USY were used for the production of solketal by facilitating reaction between glycerol and acetone at 353 K. However, these catalysts are not very effective due to limited glycerol conversions and time taken for this reaction is very high (6 h).
Reference may be made to G. Vicente, J. A. Melero, G. Morales, M. Paniagua and E. Martin, Green Chem., 2010, 12, 899 where sulfonic acid modified silca samples were used for the production of solketal from glycerol at 343 K. Though the catalysts exhibited higher glycerol conversions 85% (mol %), the cost involved in the synthesis of catalyst is high with lengthy synthesis procedures.
Based on the prior art details and drawback mentioned above, the object of the present invention is to provide a novel sulfonated carbon silica (SCS) composite material and a process for the preparation of such SCS composite material. Another object of the present invention is to provide at least one industrial application of the novel SCS composite material thus developed.